Apparatus and method for recovering precious metals



Jill -.24, 1928.

J. E. HOPKINS APPARATUS AND METHOD FOR RECOVFRiNG PRECIOUS METALS 2 Sheets-Sheet Filed Jul 24. 1928. 1,678,142

' Y J. E. HOPKINS v APPARATUS AND METHOD FOR RECOVERING PRECIOUS METALS Filed June 21, 1926 v 2 Sheets-Sheet 2 kind.

l atented duly 2 i,

APPARATUS AND METHOD FOR RECOVERING PRECIOUS METALS EMES E. HOPKINS, OF DENVER, COLORADO.

Application filed June 21, 1926. Serial No. 117,383.

This invention relates to improvements in machines for recovering gold and platinum values from auri'lerous and platiniiferous materials and sands.

It is well known to those versed in this art that gold will quite readily form an amalgam, with mercury or quicksilver and it is equally well known that platinum will not form an amalgam.

it has, therefore, been aossible to recover gold values by means whic 1 permits the gold to come into direct contact with mercury, but this has failed to save the platinum values which are often of greater value than the gold.

\Vhon sodiunris added to, quicksilver it intensities the action thereof and greatly increases its ziiiinity for gold. The sodium amalgam also has an atlinity for platinum so that it the latter comes into contact; with it, it will be amalgamated. This is be licved to be due to the fact that there is an affinity between the sodium and the platinum, which causes the sodium to form a coating on the platinum particles and, since there is a strong aliinity between the mercury and the sodium, the sodium coated particles of platinum will combine with the mercury. It is evident that it a sodium au'ialgam containing platinum is subjected to some treatment that will remove the sodium that the platinum will separate from the mercury. This is taken advantage of and the sodium platinum amalgam is sub- :jectcd to the action of water which combines with the sodium forming sodium-i hydroxide and hydrogen It is the object of this invention to pro duce a machine for the recovery of gold and platinum values which shall be so const'ructed that it will continuously renew the sodium in the mercury so as to providea continuous supply of sodium amalgam which is then delivered to the anuilgamating device or separator. This production of sodium and nascent sodium amalgam is'produeed by electrolytic means in the manner. to be presently described.

My invention. can be most clearly doscribed and will be most.readily .undcrstood when reference is had to the accompanying drawings in which the preferred-'embOdiment has been illustrated and in which:

Fig. l is a top plan view of the combined anialganiator and sodium amalgam generator Fig. Fig. l;

2 is a section taken on line 2 2,

a section taken on line 33, Fig. l; 7

Fig. at is a diametrical section of the mert'e'ury tank designated 54 in the drawing as taken on line 14, Fig. 1;

Fig. 5 is a section taken on line 5-5, l lg. l;

Fig. 6 is a Wiring diagram; and

Fig. 7 is a longitudinal section through one of the electrolytic cells and is taken on line 7-'i, Fig. 3.

in the drawings the supporting framework has been designated as a. Wholeby. the numeral 1 as there appears to be no necessity for identifying all of the parts thereof. Supported by this'framework. is a receptacle or hopper 2 which contains the pulp to be treated, a chute 3 extends from one side of the hopper 2 and its bottom may be formed by an, extension of the bottom of the hop per. The .wall lofthe hopper has its lower edge spaced from the bottom so as to provide a slot 5through which the pulp may flow. An adjustable gate 6 serves to determine the rate at "which the pulp flows from the lower end of the chute.

Located directly below the end of chute 3 is a recovery table consisting of a copper plate 7 whose upper surface has been amalgamated. The upper end of the plate 7 is bent upwardly in the manner indicated by numeral 8 so as to prevent leakage and its sides are secured to the side pieces 9 and 10. The lower edge of .the plate 7 rests on the top of the upper wall of the trough '11 and is curved downwardly in the manner indicated at 12. A battle bar 13 extends between the sides 9 and 10 directly over the center line of the trough 11 and serves to force; the pulp to pass down under and against the sodium amalgam whose upper surface is indicated by line lt in Fig. 5., After passing underneath the batiie bar 13, the pulp flows over the edge 15 and onto the plate 7 which is located directly below and thence underneath the baffle bar 13 from which it flows onto the chute 16. As many of these plates and troughs mayjbe used as may be found to be necessary, but I have shown two as an example.

Supported onthe framework 1 in parallel relation with the amalgamator which has been partially described above is an electrolytic device which serves to produce the sodium amalgam. This device 'will be best understood when reference is bad to the section shown in Fig. 3, and consists of a tank 17 which serves as a 'reservoir for a solution of sodium chloride. This tank has a faucet 18 which islocated directly above the electrolytic cell 19. This cell has a carbon anode 20 that extends longitudinally thereof'and is connected with the positive pole of a direct current source 21 (Fig. 6) by means of a wire 22. The cell contains a quantity of mercury 23 which is connected to the negative pole of the current supply by means of the conductor 24. A launder 25 is secured at-its upper end to the lower wall of the cell19 and serves to carry the brine from cell 19 to a similar cell 19 that is located at a lower level. It is the intention to have the same number of electrolytic cells as there are plates 7 although it is possible to have a single cell for serving a plurality of plates. The lowercell has been designated by 19 and the other elements are indicated by the same reference numerals as the corresponding elements in the upper cell but to which the letter A has been added. From the lower cell 19 a launder 26 extends to the reservoir 27. A pump 28 which is operated from ower derlved'from the motor 29 has its inta re port connectedwith the reservoir 27 by means of a pipe 30 and its outlet port connected with the tank 17 by means of a pipe 31. A branch pipe 32 extends from the pipe 31 to the reservoir 27 and is controlled by the valve 33. The object of the by-pass 82 is to permit the delivery to tank 17 to be regulated so that the level of the brine will remain substantially constant.

A tank 34: is supported on the framework l-at a point above the level of the mercury in the uppermost cell 19 and serves as a reservoir or supply for the IIICICUIY. A pipe 35 extends to the cell 19 and is controlled by a valve 36. A pipe 37 branches from the pipe 35 and this is controlled by a valve 38. lVhen the machine is in operation, mercury will flow from the tank 34 to the cells 19 and 19 and the rate of flow will be regulated by valves 36 and 38.

Referring now to Fig. 7, it will be seen that the cell 19 is provided with an opening 39 at one end and near the bottom. A pipe 40 is connected with this opening and has an upward bend 41 which determines the level of the mercury which must be a short distance below the lower edge of the anode 20". Pipe 40 extends over onto the plate '7 where it terminates in a perforated section 42. This section of pipe has its outer end plugged and is provided with a plurality of small holes 43 which are located on top and through which the mercury esca es onto the plate 7. From the cell 19 a simi ar pipe 40 extends. The corresponding parts of this pipe have the same reference numerals as those given above, but with the letter A attached. i

The mercury that emerges through the holes 43fal1s upon the amalgamated surface of plate 7 and flows down into the trough 11.

Referring now more particularly to Fig. 5, it will be observed that the bottom of trough ll is inclined from the ends to the middle point, which 1.115 been indicated by numeral 44. A hole extends through the bottom at point 44. and to this a valve 15 is connected. A pipe 46 extends from this valve to the clean-out 4:7 to whose lower end or bottom a stop cock 48 is secured. A pipe 49 has its lower end connected with the clean-out 47 and its upper end bent into a gooseneck 50 whose height determines the level 1 1 of the mercury. The end of the gooseneck terminates over the inclined trough 51.

The lower end of the trough 5. has an opening 52 from which a pipe 53 extends downwardly and terminates a short distance below the upper end of the tank 54:. A conicalcanvas strainer 55 is secured to the upper end of the tank 54 in the manner shown in Fig. 4. A drain cock 56 is connected to the bottom of the tank 54 and is employed when the tank is to be drained.

From the tank 54 a pipe 57 extends to the pan 58 which can be subjected to aspray of water from the pipe 59. From the pan 58 a pipe, 60 extends to the mercury pump 61, which is driven from the motor 62. This pump discharges the mercury through pipes 63 and 64 into tank 3d from which it flows into the cells 19 and 19*.

Let us now assume that the parts are assembled in the manner shown and described and that the hopper 12 is filled with pulp meaning pulverized ore mixed with water containing metallic gold and platinum; that tank 17 is filled with a sodium chloride brine and that tank 3% contains mercury. The generator 21 is connected with the anodes 20 and the mercury cathodes 23. The faucet 18 is opened and brine is allowed to flow. This brine fills the cell I9 and overflows onto the launder 25 from which it enters the cell 19 and from this flows to the reservoir 27. The pump 28 serves to return the brine to the tank 17. The stop cocks 36 and 38 are now opened so as to allow mercury to flow into the cells through pipes 37 and 37%.

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. Since the salt solution from] tank 17 is a conductor, an electric current will flow from the anodes 20 and 20 to the cathodes 23 and 23 and this Will disassociate the sodium chloride, liberating the chlorine gas, and.

transferring the sodium to the cathode.

The gas may he removed by suitable means While the sodium amalgam takes the course above described pulp flows from the hopp r 2 down onto the plate 7 underneath the baille block 13, thence down over plate 7 underneath baille block l? and onto the chute 16. l/Vhcn the pulp comes in contact with the sodium amalgam on the plates, the Water combines with the sodium and forms sodium hydroxide which is a powerful clcansing'medium and removes any oily film from the gold and platinum whereby the metal itself becomes exposed so that it will be acted upon by the amalgam. When the pulp passes underneath the battle plates 13, 13 it is forced against the surface of the amalgam so that the latter comes into contact with the gold and platinum. The greater part of the values are recovered on the uppermost plate and by using several plates in series a thorough recovery can be obtained.

As the amalgam flows from the trough 11, 11*, it passes through pipe 46 into the clean-out trap 47 where the yalues of gold and platinum settle to the bottomdue to their great density. The mercury continues through pipe 49 and. flows into the trough 51 and down into the canvas strainer 55 Where any large particles are separated.

The mercury that passes through the canvas strainer enters the tank 54 where further separation takes place and from which the settlinqs may be removed through the cock 56. The lighter mercury or sodium amalganrflows through pipe 57 to the pan'58 where the action of the, 'atcr spray re-. moves any :trace of sodium that may still i be present and since mercury alone has no I want to call particular attention to the.

fact that there is a continuous supply of heretofore been very dillicult nascent sodium amalgamavhich is supplied tothe separator, and which, when subjected to the action of the water in the pulp, resuits in the production of sodium hydroxide which dissolves any grease or fat that may be on the metal particles Y L The sodium amalgam, as above explained, is more active than mercury and has the property of combining with platinum so that these values will he recovered. This, thcrefore, makes this apparatus and method very valuable in platinum mining; as it has to recover the platinum.

Having now described the invention what is claimed as new is:

1. 'In combination, a. plurality of amalga mating plates in tandem, means for flowing pulp containing values over said plates in succession, a means for preparing allrali metal amalgam and means for conveying said amalgam directly from said preparing incaus independently to the head of each of said plates and distributing it thcrcover.

2. In 'comhination, a plurality oi amalgziniating plates in tandem, means for lion'- ing pulp containing yalues over said plates in succession, a means forpreparing alkali.

metal amalgam, means for conveying said amalgam directly from said preparing means independently to the head of each of said plates and distributing it thcreover, and a traplietween each two plates for catching; the mercury and metal amalgam and allow ing the pulp stream to pass on,

llll

In combination a plurality of. inclined amalgamatine' plates in tandem, means for flowingpulp over said plates in succession, v

a conduit for sodium amalgam transversely" arranged at the head of each plate and open to allow the amalgam to pass to theiplate, means for protecting said conduit. from the pulp stream as it is fed to the plate, means for preparing sodium amalgam-and means for coi'iveyingr said amalgam directly from said preparingmca-ns and independently to said conduit'of each plate.

4. In combination, a plurality of inclined amalgamating plates positioned to codperate so that the material to be treated may pass from the tail of one --to the head of another,

means for flowing pulp containing values over-said plates in succession, a means for preparing alkaline metal amalgam, and a means For conveying said amalgam directly from id preparing means independently to the lice-l of each of said plates'and distrilouting it thereover.

"5. In combination, a plurality of amals gramating plate sections positioned to cooperate o that the material to he treated may pass from one to .the other, means for lion in; pulp containing values over said plate sections in succession, means for preparingalkali metal amalgam, and means for conreying said amalgam directly from said preparing ineans independently to each of said plate sections and distributing it thereover.

6. The process of flowing wet pulp over an extended IllQILHI'y surface and feeding freshly prepared sodium amalgam independently to the surface in proximity to the point of delivering the pulp'to said surface, and at a plurality of spaced intervals along the 10 path of flow to maintain the mercury surface at maximum efiiciency.

' In testimony whereof I affix my signature. I JAMES E. HOPKINS. 

